mu-HEAVY CHAIN DISEASE ASSOCIATED WITH SYSTEMIC AMYLOIDOSIS AND NON-AMYLOID DEPOSITS. DIFFICULTIES IN DIAGNOSIS AND THERAPY

Introduction. Heavy-chain diseases (HCDs) are rare B-cell lymphoproliferative diseases that do not have a classical clinical picture. A characteristic feature of this disease is the secretion of fragmented heavy chains of various immunoglobulin isotypes. Currently, there are four known variants of this disease: mu, gamma, alpha, and delta. Aim. To describe the clinical observation of mu-HCD, hidden under the mask of systemic amyloidosis, and the associated difficulties of primary diagnosis. Main Findings. A rare clinical case of mu-HCD in combination with systemic amyloidosis (light chain amyloidosis-AL), transthyretin amyloidosis (transthyretin amyloidosis-ATTR), and non-amyloid deposits in a 64-year-old patient is presented. The severity of the condition was due to the clinical picture of chronic heart failure, polyneuropathy. Upon examination, Waldenstrom's macroglobulinemia was diagnosed while a diagnosis of amyloidosis was not established. Immuno-chemotherapy was performed under the RB program (rituximab and bendamustine). The effect of the therapy was minimal and short-term. The patient's condition progressively worsened, and the patient died due to acute cardiovascular failure. The main diagnosis was revised in favor of mu-HCD. The autopsy revealed widespread amyloid and non-amyloid lesions of organs and tissues.